It was so on the titanic HBO series “John Adams” and it is true again on its summer movie “Into the Storm.” In “John Adams,” Abigail Adams (Laura Linney) stood by her politician husband and eventual president, offering counsel, chiding him when his natural crankiness overwhelmed his reason and raising their children, often alone for years at a time while John (Paul Giamatti) negotiated treaties and did America’s bidding in Europe.

“Into the Storm” finds Clementine Churchill (Janet McTeer) standing by her man, the Prime Minister Winston Churchill (Brendan Gleeson) at the end of World War II, with an election coming up -one that he will lose–and, in flashbacks, during the war, when all of Britain cheered him on as he fended off the Nazis.

“Clemmie tells him, ‘If you win the election, I don’t know we’ll survive. If you lose the election, I don’t know how we’ll survive.’ It’s interesting, isn’t it? The behavior you’ll put up in extremis, you will not put up with in peacetime,” McTeer says.

HBO has had enormous success with these biopics about famous men and their stalwart women. In fact, “Into the Storm” is the sequel to its award-winning 2002 movie about the Churchills, “The Gathering Storm,” which starred Albert Finney, who won an Emmy as Winston, and Vanessa Redgrave as Clementine, or, as she is called, Clemmie.

Janet McTeer, a Tony nominee this year for her powerful performance in the play “Mary Stuart,” has something in common with Redgrave, besides them both having played the same role. They are both exceedingly tall. McTeer is six-feet-one; Redgrave, almost that tall. McTeer, 48, says that when she has to go British costume houses for a fitting, “they just pull out Vanessa’s stuff. I love it. She’s been one of my major icons.”

While Mary Stuart is a role distinguished by athletic passion and athletic grace, Clementine Churchill is the opposite: a woman so reserved she looks like she might fade into the background, until it becomes clear, as McTeer says, “Winston couldn’t really cope without her. When she wasn’t around, he didn’t take calls.”

McTeer, who won a Tony for her star turn in Ibsen’s “A Doll House” in 1997, is talking about the Churchills at a Times Square bistro where she gobbles up eggs benedict and coffee. “Grumpy old bugger he was. I think he must have been an absolute nightmare,” she says. “He drank a bottle of whisky a day. That will make you cranky.”

Just as the assertive McTeer could not be more different than the role she’s playing in “Into the Storm,” Brendan Gleeson (“In Bruges”), who plays the grumpy old bugger, is a delightful raconteur full of Irish mischief. He calls from the Four Seasons in Beverly Hills to say how intimidated he was by the prospect of playing Churchill. Before he rehearsed with McTeer for two weeks, he worked with vocal coach Joan Washington just to get the voice right.

“The power of words is so central to Churchill’s achievement,” says Gleeson of the Nobel-winning Churchill. “I started from the point of just mimicry. It was a beneficial that a lot of things were recorded. The fundamental thing is to get the accent into your own pitch.”

Gleeson, 54, has played historical figures before, most notably Michael Collins in a TV movie “The Treaty” and the Irish criminal Martin Cahill in “The General.” The 54-year-old actor says, “I have a great attraction to real-life characters. What you find is the plots write themselves. Nobody can say, ‘That’s ludicrous,’ because it’s always happened.”

McTeer had to tone down her tawny athleticism to play Clemmie, but Gleeson had to put on weight to play the portly Churchill, something he said he did with “great aplomb. I don’t really have a problem putting on weight. I haven’t got rid of it yet. Don’t worry. It’ll happen.”

McTeer, who is single and lives in London, and Gleeson, who is married with four children and lives in Dublin, have become “great mates,” as she says, from working together. “I’d work with him again in a heartbeat.”

“Janet was supportive and full-on,” Gleeson says. “Her performance had nothing to do with her height. But it was great to get someone who was so appropriate vertically.”